A mobile communication device and its serving base station wirelessly communicate to provide voice, Internet, email, text, video, and other communication services. As the mobile communication device moves about, the serving base station hands-off the mobile communication device to another target base station. After the hand-off, the target base station then becomes the serving base station, and subsequently, this new serving base station will hand-off the mobile communication device to another target base station.
In some communication systems, the mobile communication device receives a list of nearby base stations from the serving base station. If the mobile communication device detects an unacceptable loss of wireless signal strength for the serving base station, then the mobile communication device selects another base station from the list having the best wireless signal strength to be the target base station. The mobile communication device then initiates a hand-off from the serving base station to the selected target base station.
Serving base stations may also initiate hand-offs when they become overloaded and need to reduce the number of mobile communications devices they serve. Typically, the overloaded base station hands-off the mobile communication devices to more lightly loaded base stations. Serving base stations may also initiate hand-offs based on low wireless signal strength.
Some communication networks have a hierarchical design where cells overlap or are nested within one another. A very large cell may contain a number of mid-sized cells, and the mid-sized cells may contain a number of very small cells. There are gaps between the very small cells that are served by the mid-sized cells or by the larger cells. There are gaps between the mid-sized cells that are served by the larger cells. The use of base station lists and signal-strength by mobile communication devices to select target base stations tends to overload the larger cells. The use of load balancing by the larger cells tends to increase network signaling and processing to unacceptable levels.
Overview
A mobile communication device wirelessly transfers user communications to a first wireless base station. The mobile communication device identifies a second wireless base station that has sufficient performance characteristics for wireless communication with the mobile communication device and that has a higher communication priority than the first wireless base station. In response, the mobile communication device initiates a hand-off from the first wireless base station to the second wireless base station. In response to the hand-off, the mobile communication device stops the wireless transfer of the user communications to the first wireless base station and wirelessly transfers additional user communications to the second wireless base station.